This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 18 |
| 5 | 54 |
| 6 | 146 |
| 7 | 391 |
| 8 | 1081 |
| 9 | 3004 |
| 10 | 8320 |
| 11 | 22984 |
| 12 | 63424 |
| 13 | 175176 |
| 14 | 484113 |
| 15 | 1337721 |
| 16 | 3695886 |
| 17 | 10210702 |
| 18 | 28209954 |
| 19 | 77940078 |
| 20 | 215337554 |
| 21 | 594943087 |
| 22 | 1643728129 |
| 23 | 4541349672 |
| 24 | 12547013504 |
| 25 | 34665373744 |
| 26 | 95774808224 |
| 27 | 264610227072 |